The answer will depend on the school and your numerical qualifications. Some schools accept students off of the wait list with substantial scholarships (and some users have negotiated a higher amount), but the general rule is to expect to pay sticker if lifted off of a wait list.

Usual no. Actually, almost never. I hear W&L did it last year to some high splitters on the WL (remember the random full-ride give aways to kids who didn't even apply lol? It was a wild cycle). But I've never actually heard of it first hand.